Socket总结归纳

——levy

一、SOCKET原理

1.什么是socket

所谓socket通常也称作\"套接字\"，用于描述IP地址和端口，是一个通信链的句柄。应用程序通常通过\"套接字\"向网络发出请求或者应答网络请求。

以J2SDK-1.3为例，Socket和ServerSocket类库位于java.net包中。ServerSocket用于服务器端，Socket是建立网络连接时使用的。在连接成功时，应用程序两端都会产生一个Socket实例，操作这个实例，完成所需的会话。对于一个网络连接来说，套接字是平等的，并没有差别，不因为在服务器端或在客户端而产生不同级别。不管是Socket还是ServerSocket它们的工作都是通过SocketImpl类及其子类完成的。 2.重要的Socket API：

java.net.Socket继承于java.lang.Object，有八个构造器，其方法并不多，下面介绍使用最频繁的三个方法，其它方法大家可以见JDK-1.3文档。

. Accept方法用于产生\"阻塞\"，直到接受到一个连接，并且返回一个客户端的Socket对象实例。\"阻塞\"是一个术语，它使程序运行暂时\"停留\"在这个地方，直到一个会话产生，然后程序继续；通常\"阻塞\"是由循环产生的。

. getInputStream方法获得网络连接输入，同时返回一个IutputStream对象实例，。 . getOutputStream方法连接的另一端将得到输入，同时返回一个OutputStream对象实例。

注意：其中getInputStream和getOutputStream方法均会产生一个IOException，它必须被捕获，因为它们返回的流对象，通常都会被另一个流对象使用。 3.如何开发一个Server-Client模型的程序 开发原理：

服务器，使用ServerSocket监听指定的端口，端口可以随意指定（由于1024以下的端口通常属于保留端口，在一些操作系统中不可以随意使用，所以建议使用大于1024的端口），等待客户连接请求，客户连接后，会话产生；在完成会话后，关闭连接。

客户端，使用Socket对网络上某一个服务器的某一个端口发出连接请求，一旦连接成功，打开会话；会话完成后，关闭Socket。客户端不需要指定打开的端口，通常临时的、动态的分配一个1024以上的端口。

二、建立模型

1.基本Server-Client模型

｛建立服务器｝

1: import java.net.*; 2: import java.io.*; 3: 4: public class Server { 5: private ServerSocket ss; 6: private Socket socket; 7: private BufferedReader in;

8: private PrintWriter out; 9: 10: public Server() { 11: try { 12: ss = new ServerSocket(10000); 13: //进入循环，这是由socket的特性决定的，进行循环监听 14: while (true) { 15: socket = ss.accept(); //accept() 监听方法 16: in = new BufferedReader(new InputStreamReader(socket.getInputStream())); 17: out = new PrintWriter(socket.getOutputStream(),true); 18: 19: String line =

in.readLine(); 20: out.println(\"you input is :\" + line); 21: out.close(); 22: in.close(); 23: socket.close(); //socket流必须关闭！ 24: } 25: ss.close(); 26: } catch

(IOException e) {} 27: } 28: 29: public static void main(String[] args) { 30: new Server(); 31: } 32: }

这个程序建立了一个服务器，它一直监听10000端口，等待用户连接。在建立连接后给客户端返回一段信息，然后结束会话。这个程序一次只能接受一个客户连接。

｛建立客户端｝

1: import java.io.*; 2: import java.net.*; 3: public class Client { 4: Socket socket; 5: BufferedReader in; 6: PrintWriter out; 7: public Client() { 8: try { 9: socket = new Socket(\"xxx.xxx.xxx.xxx\ //服务器地址和端口号 10: in = new BufferedReader(new InputStreamReader(socket.getInputStream())); 11: out = new PrintWriter(socket.getOutputStream(),true); 12: BufferedReader line = new BufferedReader(new InputStreamReader(System.in)); 13: out.println(line.readLine()); 14: line.close(); 15: out.close(); 16: in.close(); 17: socket.close(); 18: } catch (IOException e) {} 19: } 20: public static void main(String[] args) { 21: new Client(); 22: } 23: }

这个客户端连接到地址为xxx.xxx.xxx.xxx的服务器，端口为10000，并从键盘输入一行信息，发送到服务器，然后接受服务器的返回信息，最后结束会话。

2.Serverd端多线程模型（解决多客户同时连接）

在实际的网络环境里，同一时间只对一个用户服务是不可行的。一个优秀的网络服务程序除了能处理用户的输入信息，还必须能够同时响应多个客户端的连接请求。在java中，实现以上功能特点是非常容易的。

设计原理：

主程序监听一端口，等待客户接入；同时构造一个线程类，准备接管会话。当一个Socket会话产生后，将这个会话交给线程处理，然后主程序继续监听。运用Thread类或Runnable接口来实现是不错的办法。

｛实现消息共性｝

1: import java.io.*; 2: import java.net.*; 3: public class Server extends ServerSocket { 4: private static final int SERVER_PORT = 10000; 5: public Server() throws

IOException { 6: super(SERVER_PORT); 7: try { 8: while (true) { 9: Socket socket = accept(); 10: new CreateServerThread(socket); 11: } 12: } catch (IOException e) {} finally { 13: close(); 14: } 15: } 16: //---

CreateServerThread 17: class CreateServerThread extends Thread { 18: private Socket client; 19: private BufferedReader in; 20: private

PrintWriter out; 21: public CreateServerThread(Socket s) throws IOException { 22: client = s; 23: in = new BufferedReader(new InputStreamReader(client.getInputStream(), \"GB2312\")); 24: out = new PrintWriter(client.getOutputStream(), true); 25: out.println(\"--- Welcome ---\");

26: start(); 27: } 28: public void run() { 29: try { 30: String line = in.readLine(); 31: while

(!line.equals(\"bye\")) { 32: String msg = createMessage(line); 33: out.println(msg); 34: line = in.readLine(); 35: } 36: out.println(\"--- See you, bye! ---\"); 37: client.close(); 38: } catch (IOException e) {} 39: } 40: private String

createMessage(String line) { 41: xxxxxxxxx; 42: } 43: } 44:

public static void main(String[] args) throws IOException { 45: new Server(); 46: } 47: }

这个程序监听10000端口，并将接入交给CreateServerThread线程运行。CreateServerThread线程接受输入，并将输入回应客户，直到客户输入\"bye\"，线程结束。我们可以在createMessage方法中，对输入进行处理，并产生结果，然后把结果返回给客户。 第三步 实现信息共享:在Socket上的实时交流

2.信息共享模型

网络的伟大之一也是信息共享，Server可以主动向所有Client广播消息，同时Client也可以向其它Client发布消息。下面看看如何开发一个可以实时传递消息的程序。

设计原理：

服务器端接受客户端的连接请求，同时启动一个线程处理这个连接，线程不停的读取客户端输入，然后把输入加入队列中，等候处理。在线程启动的同时将线程加入队列中，以便在需要的时候定位和取出。

｛源码｝

1: import java.io.*; 2: import java.net.*; 3: import java.util.*; 4: import java.lang.*; 5: public class Server extends ServerSocket { 6: private static ArrayList User_List = new ArrayList(); 7: private static ArrayList Threader = new ArrayList(); 8: private static LinkedList Message_Array = new LinkedList(); 9: private static int Thread_Counter = 0; 10: private static boolean isClear = true; 11: protected static final int SERVER_PORT = 10000; 12: protected FileOutputStream LOG_FILE = new FileOutputStream(\"d:/connect.logrue); 13: public Server() throws

FileNotFoundException, IOException { 14: super(SERVER_PORT); 15: new Broadcast(); 16: //append connection log 17: Calendar now = Calendar.getInstance(); 18: String str = \"[\" + now.getTime().toString() + \"] Accepted a

connection\\015\\012\"; 19: byte[] tmp = str.getBytes(); 20:

LOG_FILE.write(tmp); 21: try { 22: while (true) { 23: Socket socket = accept(); 24: new CreateServerThread(socket); 25: } 26: } finally { 27: close(); 28: } 29: } 30: public static void main(String[] args) throws IOException { 31: new Server(); 32: } 33: //--- Broadcast 34: class Broadcast extends Thread { 35: public Broadcast() { 36: start();

37: } 38: public void run() { 39: while (true) { 40:

if (!isClear) { 41: String tmp = (String)Message_Array.getFirst(); 42: for (int i = 0; i < Threader.size(); i++) { 43: CreateServerThread client = (CreateServerThread)Threader.get(i); 44: client.sendMessage(tmp); 45: } 46: Message_Array.removeFirst(); 47: isClear = Message_Array.size() > 0 ? false : true; 48: } 49: } 50: } 51: }

52: //--- CreateServerThread 53: class CreateServerThread extends Thread { 54: private Socket client; 55: private BufferedReader in; 56: private PrintWriter out; 57: private String Username; 58: public

CreateServerThread(Socket s) throws IOException { 59: client = s; 60: in = new BufferedReader(new InputStreamReader(client.getInputStream())); 61: out = new PrintWriter(client.getOutputStream(), true); 62: out.println(\"---

Welcome to this chatroom ---\"); 63: out.println(\"Input your nickname:\"); 64: start(); 65: } 66: public void sendMessage(String msg) { 67: out.println(msg); 68: } 69: public void run() { 70: try

{ 71: int flag = 0; 72: Thread_Counter++; 73: String line = in.readLine(); 74: while (!line.equals(\"bye\")) { 75: if (line.equals(\"l\")) { 76: out.println(listOnlineUsers()); 77: line = in.readLine(); 78: continue; 79: } 80: if (flag++ == 0) { 81: Username = line;

82: User_List.add(Username); 83: out.println(listOnlineUsers()); 84: Threader.add(this); 85: pushMessage(\"[< \" + Username + \" come on in >]\"); 86: } else { 87: pushMessage(\"<\" + Username + \">\" + line); 88: } 89: line = in.readLine(); 90: } 91: out.println(\"--- See you, bye! ---\"); 92: client.close(); 93: } catch (IOException e) {} finally { 94: try { 95: client.close(); 96: } catch (IOException e) {} 97: Thread_Counter--;

98: Threader.remove(this); 99: User_List.remove(Username); 100: pushMessage(\"[< \" + Username + \" left>]\");

101: } 102: } 103: private String listOnlineUsers() { 104: String s =\"-+- Online list -+-\\015\\012\"; 105: for (int i = 0; i < User_List.size(); i++)

{ 106: s += \"[\" + User_List.get(i) + \"]\\015\\012\"; 107: } 108: s += \"-+---------------------+-\"; 109: return s; 110: } 111: private

void pushMessage(String msg) { 112: Message_Array.addLast(msg); 113: isClear = false; 114: } 115: } 116: }

这就是程序运行后，多用户登陆并且输入信息后的屏幕。实现了信息的实时广播。用户输入\"l\"就可以列出在线人员表。

三、整体直观代码块（socket模型）

｛客户端socket类｝

1: import java.io.*; 2: import java.net.*; 3: 4: public class NovelClient { 5: 6: 7: private ObjectOutputStream output; 8: private ObjectInputStream input; 9: private Socket socket; 10: private Object o; 11: 12: 13:

/** 14: * socket流声明 15: */ 16: public NovelClient(){ 17:

try { 18: InetAddress addr = InetAddress.getLocalHost(); 19: String ip=addr.getHostAddress().toString(); 20: socket=new Socket(ip,8000); 21: } catch (UnknownHostException e) { 22: e.printStackTrace(); 23: } catch (IOException e) { 24: e.printStackTrace(); 25: } 26: } 27: 28: public Object sendAndRead(Object o){ 29: try

{ 30: output=new ObjectOutputStream(socket.getOutputStream()); 31: output.writeObject(o); 32: output.flush(); 33: input=new ObjectInputStream(socket.getInputStream()); 34: o=(Object) input.readObject(); 35: } catch (IOException e) { 36: e.printStackTrace(); 37: } catch

(ClassNotFoundException e) { 38: e.printStackTrace(); 39: }finally{ 40: output.close(); 41: input.close(); 42: } 43: return o; 44: }

｛服务器端socket类｝

1: 2: import java.io.IOException; 3: import java.net.ServerSocket; 4: import java.net.Socket; 5: /** 6: * Socket Class 7: * @author oracle 8: * 9: */ 10: public class Server { 11: 12: private static ServerSocket serversocket; 13: private static Socket scoket; 14: 15: public static void serverStart(){ 16: try { 17: serversocket =new ServerSocket(7566); 18: System.out.println(\"server start...\"); 19: while(true){ 20: scoket=serversocket.accept(); 21: ServerThread serverthread=new

ServerThread(scoket); 22: Thread thread=new Thread(serverthread); 23: thread.start(); 24: } 25: } catch (IOException e) { 26: e.printStackTrace(); 27: } 28: } 29: 30: public static void main(String []args){ 31: Server.serverStart(); 32: } 33: 34: }

｛服务器端线程类｝

1: import java.io.*; 2: import java.net.Socket; 3: 4: public class ServerThread implements Runnable { 5: 6: private Socket socket; 7: private ObjectInputStream in; 8: private ObjectOutputStream out; 9: private Objecet o; 10: 11: public ServerThread (Socket socket) { 12: this.socket=socket;

13: } 14: 15: @Override 16: public void run() { 17: serverThread(); 18: } 19: 20: private void serverThread() { 21: 22: try { 23: in=new ObjectInputStream(socket.getInputStream()); 24: o=(Object) in.readObject(); 25: 26: ObjectOutputStream(socket.getOutputStream()); 27: out.flush(); 29: } catch (IOException e) { 30: 31: } catch (ClassNotFoundException e) { 32: 33: } 34: } 35: }

声明：最后这个是我自己写的，为了以后理解时候用的。

out=new

out.writeObject(o); 28: e.printStackTrace(); e.printStackTrace();